Design of molecularly imprinted polymer grafts with embedded gold nanoparticles through the interfacial chemistry of aryl diazonium salts

A novel strategy is described for the preparation of highly sensitive molecularly imprinted (MIPs) sensors for dopamine. It combines mercaptobenzene diazonium salt as a coupling agent for immobilizing gold nanoparticles to gold electrodes and benzoyl benzene diazonium salt as photoinitiator of radical polymerization at the said gold nanoparticle-decorated gold electrodes. The MIP films were prepared by surface-initiated photopolymerization (SIPP) of methacrylic acid (MAA) as functional monomer (F) for dopamine (DA) the template molecule (T), and ethylene glycol dimethacrylate (EGDMA), the crosslinker (C). Dimethylaniline was employed as a hydrogen donor. The specificity and selectivity were demonstrated by square wave voltammetry (SWV). The detection limit was 0.35 nmol L^-1 (0.054 ng mL⁻¹). The sensor layers are stable and adherent to the surface through aryl layers. The originality and advantage of the process lie in the use of aryl diazonium salt as coupling agents for anchroring nanoparticles and MIP layers to the electrode surface in a simple and efficient way which ensures high sensing performance together with good surface-MIP adhesion. The same strategy can be extended to a broad range of templates.     

浅层地震勘探在第四纪松散地层划分中的应用

采用浅层地震勘探技术在矿区第四纪松散地层进行地层、构造和地下水勘探。通过以反射波法为主,折射波、面波法为辅的综合地震勘探方法较为准确地对勘探区地层进行了划分,结合钻孔勘探,有效揭露了矿区第四系地层厚度及地层空间展布特征。地震勘探将矿区地层划分为三大套岩性层,分别为第四系全新统地层、上更新统地层和元古界基岩层,与钻孔勘探揭露地层基本一致。钻孔K1处地震法解释第四纪地层厚度为240m,钻孔勘探揭露厚度为241．37m,验证了地震勘探的可靠性。     

中国北方第四纪磁性地层记录的 古地磁极倒转与气候变化耦合关系

应用古地磁学原理,分析了中国北方第四纪黄土、泥河湾盆地、黄海陆架磁性地层记录的古地 磁极倒转与气候变化之间的关系。研究表明第四纪古地磁极倒转与气候变化有一定的耦合关系: Matuyama/Gauss极性界限、Brunhes/Matuyama极性界限与第四纪气候变冷期相对应,Matuyama负极 性时中的正极性亚时及Brunhes正极性时中的负极性亚时与气候变暖期相一致。因而,第四纪古地磁 极倒转可能是第四纪气候冷暖波动变化的主要驱动因素之一。     

HPLC analysis of quaternary ammonium surfactants with the evaporative light scattering detector

A normal-phase high-pressure liquid chromatography technique has been elaborated for the separation of quaternary ammonium surfactants. The separation was achieved on a bonded polyphenol silica gel column with gradient elution and evaporative light-scattering (ELS) detection. The proposed method has been applied to the quantitative determination of low levels of monoalkyltrimethylammonium and trialkylmethylammonium chlorides in dialkyldimethylammonium chloride.     

The Synergistic Effect Between Phosphonocarboxylic Acid Salts and Fatty Amines for the Corrosion Protection of a Carbon Steel

This work was carried out to have a better understanding of the synergistic effect between phosphonocarboxylic acid salts (PCAS) and fatty amines (FA) for the corrosion protection of a carbon steel in a 200 mg l^–1 NaCl solution. These compounds, combined with a biocide at low dosage, are used for water treatment in cooling circuits. First, electrochemical impedance measurements were performed to verify the inhibitive properties of the mixtures. Among the different concentrations tested, maximum efficiency was reached for the mixture containing 200 mg l^–1 PCAS + 50 mg l^–1 FA. Then, electrochemical measurements (current—voltage curves and impedance diagrams) were combined with surface analysis (X-ray photoelectron spectroscopy) for each compound at the optimized concentrations and for the mixture. In the presence of amines, the iron oxide/hydroxide layer remained porous and the inhibition efficiency was relatively low. The FA acted by repelling the water molecules from the interface. PCAS sealed the pores of the oxide layer by forming a chelate. Thus, the growth of the inhibitive layer was limited but the efficiency was higher than for the FA alone. For the optimized mixture, the formation of the chelate was enhanced and the protective properties of the layer improved. A competitive adsorption mechanism was proposed to account for the synergistic effect observed in the presence of both compounds.     

Polymer electrolytes from PEO and novel quaternary ammonium iodides for dye-sensitized solar cells

Polymer electrolytes were prepared by blending high molecular weight poly(ethylene oxide) (PEO) and a series of novel quaternary ammonium iodides, the polysiloxanes with oligo(oxyethylene) side chains and quaternary ammonium groups. X-ray diffraction (XRD) measurements ensured relatively low crystallinity when the quaternary ammonium iodides were incorporated into the PEO host. The ionic conductivity of these complexes was improved with the addition of plasticizers. The improvement in the ionic conductivity was determined by the polarity, viscosity and amounts of plasticizers. A plasticized electrolyte containing the novel quaternary ammonium iodide was successfully used in fabricating a quasi-solid-state dye-sensitized solar cell for the first time. The fill factor and energy conversion efficiency of the cell were calculated to be 0.68 and 1.39%, respectively.     

Modelling the transport of carbonic acid anions through anion-exchange membranes

Electrodiffusion of carbonate and bicarbonate anions through anion-exchange membranes (AEM) is described on the basis of the Nernst-Planck equations taking into account coupled hydrolysis reactions in the external diffusion boundary layers (DBLs) and internal pore solution. The model supposes local electroneutrality as well as chemical and thermodynamic equilibrium. The transport is considered in three layers being an anion exchange membrane and two adjoining diffusion layers. A mechanism of competitive transport of HCO₃⁻ and CO₃²⁻ anions through the membrane which takes into account Donnan exclusion of H⁺ ions is proposed. It is predicted that the pH of the depleting solution decreases and that of the concentrating solution increases during electrodialysis (ED). Eventual deviations from local electroneutrality and local chemical equilibrium are discussed.     

Time-dependent viscosity of structured clay suspensions

Time-dependent viscosity of structured clay suspensions under a fixed shear was revealed in the prepared slurry samples of clay lenses from the Athabasca oil sands deposit, differing from thixotropic or rheopectic suspensions. At a lower salt (Na or Ca) concentration, the viscosity oscillated with time, which was slowly damped with increasing salt concentrations. The viscosity increased without reaching a maximum plateau, even after a run of a few hours. At 1000 ppm Na concentration, a maximum viscosity was reached, followed by viscosity fluctuation within a narrow range to approach an equilibrium value with time. Both sample ageing and shear history affected the slurry viscosity. It was speculated that the Brownian motion of colloidal clay particles and the applied shear induced rearrangement and continued formation of clay microstructures with time, due to the rotation of anisotropic colloidal clay particles under simple shear flow. Its implications to oil sands research and operation were briefly discussed.     

Synthesis of a (Ti,Mo)B2 coating by electro-codeposition in NaCl–KCl–AlCl3–MoO3 melt containing TiB2 nanoparticles

This paper demonstrates the availability of electro-codeposition (i.e., the simultaneous occurrence of electrophoretic deposition of nanoparticles and electrochemical deposition of metal ions) in molten salts without the assistance of stirring of the bath. In molten NaCl–KCl–AlCl₃–MoO₃ system containing TiB₂ nanoparticles at 710°C, the electro-codeposition of TiB₂ nanoparticles and Mo(VI) ions has been achieved, and a (Ti, Mo)B₂ coating has been prepared.